f volatile ammonia are, therefore, in its case not so
great as we have seen them to be in the case of the "hot" horse-dung.
Notwithstanding this fact, much of what has been said on the use of
preservatives for horse-manure may be also applied to the cow-dung. This
is owing to the fact that the dung is allowed to accumulate in the court
for some time. The amount of straw it is advisable to use as litter
varies, as has been said, from 6 to 10 lb. per day. The best method of
calculating this amount, according to Dr Heiden, is by taking one-third
of the total weight of the dry substance of the food. The above
authority also recommends that the straw is best applied in blocks of
about one foot in length; and this for the following reasons:--

1. The strewing of it is more convenient.

2. The absorption of the fluid portion is more complete.

3. The cleaning out of the manure from the byre is easier.

4. The manure is more easily distributed when applied to the field.

Among the advantages incidental to allowing the manure to accumulate in
the court may be mentioned the following:--

1. The more thorough absorption of the urine by the straw, and,
consequently, the more uniform mixture which will be thus effected of
the more valuable urine with the less valuable solid excreta.

2. A certain retardation of decomposition effected by the treading under
foot of the manure.

3. The protection of the manure from rain and wind, and the securing of
a uniform temperature.

Against those advantages must be placed the risk of seriously affecting
the health of the animal. Although this is a point of very great
importance, it scarcely falls within the scope of this work. It may be
pointed out, however, that the judicious use of some of the chemical
fixers previously referred to may do much to keep the air of the byre or
court free of noxious gases.[158]

3. _Pig-manure._

The food of the pig is so very variable in its character that it is
wellnigh impossible to obtain anything like an average analysis of its
excrements. When the food of the pig is rich, then the manure may be
quite equal in quality to the other manures. According to Boussingault,
the total amount of excrements, on an average, voided by a pig in
twenty-four hours is about 8.32 lb., of which 1.5 lb. is dry
matter.[159] The amount of nitrogen these excrements contain is only .05
lb., and of mineral ingredients .313 lb. If we take the amount of straw
most suitab